program p25;
uses Crt;
label 1;
var h1,m1,h2,m2,hod,min:byte;
    p1,p2,rozdil:longint;

begin
1:
clrscr;
repeat
write('Kolikatou hodinu prisel ? ');readln(h1);
write('Kolikatou minutu prisel ? ');readln(m1);
until (h1>=0) and (h1<24) and (m1>=0) and (m1<60);
repeat
write('Kolikatou hodinu odesel ? ');readln(h2);
write('Kolikatou minutu odesel ? ');readln(m2);
until (h2>=0) and (h2<24) and (m2>=0) and (m2<60);
p1:=h1*60+m1; { tolik minut od pulnoci - prichod }
p2:=h2*60+m2; { tolik minut od pulnoci - odchod }
if p2<p1 then goto 1; { chyba - odchod drive nez prichod }
rozdil:=p2-p1; { tolik minut v praci }
hod:=trunc(rozdil/60);
min:=rozdil-(60*hod);
writeln('V praci byl celkem ',hod,' hod. a ',min,' min.');
repeat until keypressed;
end.